This invention relates to improvements in high pressure mechanical seal assemblies to prevent uncontrolled leakage of high pressure fluid along a rotating shaft and is particularly directed to an improvement in a mechanical seal assembly such as disclosed in the U.S. Pat. No. 4,586,719 patent of Marsi et al, which issued on May 6, 1986.
As stated in the Marsi et al patent, the patented mechanical seal assembly was developed for use in nuclear reactor coolant pumps, boiler recirculator pumps and pipeline pumps to meet the requirements for extreme and widely changing conditions of pressures and temperatures, where the pump shaft will move axially and may also wobble or deflect radially under such conditions. To operate under such conditions, the patented mechanical seal assembly has a rotatable seal ring resiliently coupled to a rotatable shaft and a non-rotatable seal ring resiliently urged axially toward the rotatable seal ring by axially-arranged identical springs received in spring pockets in a spring retainer. The seal rings separate high pressure fluid from a lower pressure fluid, and have opposed seal faces lubricated by the pump fluid. The outer surface of the rotatable seal ring is enclosed within and is resiliently coupled to an encircling cylindrical member and the non-rotatable seal ring is sealed inside another encircling cylindrical member. A balance sleeve, loosely fitted in the seal flange, supports the non-rotatable seal ring and allows angular misalignment between the shaft and balance sleeve during operation of the seal assembly.